Wireless transceiver and frequency plan

Abstract

The present invention provides for an improved transceiver architecture using fewer frequency synthesizers. The number of frequency synthesizers is reduced by utilizing an existing frequency source having a frequency slightly offset from the ideal sampling frequency. In one embodiment, an improved transceiver capable of communicating CDMA encoded signals is presented. The transceiver includes a first frequency synthesizer producing a first mixing tone, a second frequency synthesizer producing a second mixing tone, a first sampling source producing a first sampling signal, and a receiving channel. The receiving channel includes a first mixer, a second mixer, and an analog to digital converter (ADC). The first mixer receives the incoming CDMA signal and the first mixing tone, producing a first IF signal. The second mixer receives the first IF signal and the second mixing tone, producing a second IF signal in response. The ADC receives the second IF signal and the first sampling signal, producing a digital data stream in response, whereby the frequency of the first sampling signal is offset from the frequency of the second IF signal, the digital data having a small amount of error associated therewith in proportion to the small amount of the frequency offset.

What is claimed is: 
     
       1. A wireless transceiver capable of transmitting CDMA signals to and receiving CDMA signals from a remote location, the wireless transceiver comprising: a first frequency synthesizer for providing a first mixing tone;   a second frequency synthesizer for providing a second mixing tone;   a first sampling source for providing a first source frequency;   a sampling circuit coupled to said first sampling source for providing a sampling signal; and   a receiving channel coupled to said first frequency synthesizer, to said second frequency synthesizer, and to said sampling source, said receiving channel comprising: a first mixer configured to received said first mixing tone and a received signal, said first mixer producing a first IF signal in response;   a second mixer configured to receive said first IF signal and said second mixing tone, said second mixer producing a second IF signal in response; and   an analog to digital converter configured to receive said second IF signal and said sampling signal and for generating a digital data stream in response, wherein if said received signal is a CDMA signal, the frequency of said sampling signal is offset from the frequency of said second IF signal.     
     
     
       2. The wireless transceiver of claim 1 further comprising: a data source for providing modulated data;   a transmitting channel coupled to said data source, to said first frequency synthesizer, and to said second frequency synthesizer, said transmitting channel comprising: a 1/8 frequency divider configured to receive said second mixing tone and to produce a one-eighth second mixing tone;   a third mixer configured to received said modulated data and said one-eighth second mixing tone, said third mixer producing an IF signal in response; and   a fourth mixer configured to receive said IF signal and said first mixing tone, said second mixer producing signals at the frequency of said transmitted signals in response.     
     
     
       3. The wireless transceiver of claim 2, wherein said received signals are CDMA signals operating between 1931.25 MHz-1988.75 MHz, said transmitted signals are CDMA signals operating between 1851.25 MHz-1908.75 MHZ, said first mixing tone operating between 1722.0 MHZ-1779.5 MHz, said second mixing tone operates at 206.8 MHz, and said sampling signal operates at a multiple of 1.2288 MHz. 
     
     
       4. The wireless transceiver of claim 3, wherein said first and second frequency synthesizers are coupled to a common reference generator operating at 19.2 MHz. 
     
     
       5. The wireless transceiver of claim 3, wherein said receiving channel further comprises: an antenna for transmitting and receiving said CDMA signals; and   a diplexer having a first terminal coupled to said antenna, a second terminal coupled to said receiving channel for passing said received CDMA signals from said antenna to said receiving channel, and a third terminal coupled to said transmitting channel for passing said transmitted signals from said transmitting channel to said antenna.   
     
     
       6. The wireless transceiver of claim 5, wherein said receiving channel further comprises: a RF circuit having an input coupled to said second terminal of said diplexer and an output coupled to said first mixer, said RF circuit providing amplification and filtering to said received signal; and   an IF circuit having an input coupled to said first mixer and an output coupled to said second mixer, said IF circuit providing amplification and filtering to said first IF signal.   
     
     
       7. The wireless transceiver of claim 1, further comprising a second sampling source coupled to said sampling circuit for providing a second source frequency. 
     
     
       8. The wireless transceiver of claim 7, wherein said received signals comprise CDMA and AMPS signals operating between 869 MHz and 894 MHz, said first sampling source operating at 1.2288 MHz and said second sampling source operating at 19.2 MHz. 
     
     
       9. The wireless transceiver of claim 8, wherein, if said received signal is a CDMA signal, said sampling circuit generates a sampling signal at an integer multiple of 1.2288 MHz and said sampling signal is not an integer multiple of said second IF frequency. 
     
     
       10. The wireless transceiver of claim 9, wherein, if said received signal is an AMPS signal, said sampling circuit generates a sampling signal at an integer multiple or divisor of 19.2 MHz and said sampling signal is an integer multiple of said second IF frequency. 
     
     
       11. The wireless transceiver of claim 10, wherein if said received signal is a CDMA signal, said first mixing tone operates between 952 MHz and 978 MHz, and said second mixing tone operates at 85.08 MHz. 
     
     
       12. The wireless transceiver of claim 11, wherein if said received signal is a AMPS signal, said first mixing tone operates between 951 MHz and 977 MHz, and said second mixing tone operates at 85.58 MHz. 
     
     
       13. The wireless transceiver of claim 12, further comprising: an antenna for transmitting and receiving said CDMA and AMPS signals; and   a diplexer having a first terminal coupled to said antenna, a second terminal coupled to said receiving channel for passing said received signals from said antenna to said receiving channel, and a third terminal coupled to said transmitting channel for passing said transmitted signals from said transmitting channel to said antenna.   
     
     
       14. The wireless transceiver of claim 13, wherein said receiving channel further comprises: a RF circuit having an input coupled to said second terminal of said diplexer and an output coupled to said first mixer, said RF circuit providing amplification and filtering to said received AMPS and CDMA signal; and   an IF circuit having an input coupled to said first mixer and an output coupled to said second mixer, said IF circuit providing amplification and filtering to said first IF signal.   
     
     
       15. In a wireless transceiver capable of receiving CDMA signal from a remote location, a method for converting an incoming signal to a digital data stream comprising the steps of: receiving an incoming signal;   synthesizing a first mixing tone;   synthesizing a second mixing tone;   generating a first sampling signal from a first sampling source; and   demodulating said incoming signal into said digital data stream, comprising the steps of: frequency mixing said incoming signal with said first mixing tone, and in response, producing a first IF signal;   frequency mixing said first IF signal with said second mixing tone, and in response, producing a second IF signal; and   applying said first sampling signal and said second IF signal to an analog to digital converter, and in response producing said digital data stream, wherein if said incoming signal is a CDMA signal, the frequency of said first sampling signal is offset from the frequency of said second IF signal.     
     
     
       16. The method of claim 15, wherein said wireless transceiver is further capable of receiving AMPS signals for a remote location, the method of converting said received signal further comprising the step of providing a second sampling source, wherein if said received signal is said AMPS signal, said step of applying comprises the step of applying said second sampling signal and said second IF signal to said analog to digital converter, the frequency of said second sampling signal being a harmonic of the frequency of said second IF signal. 
     
     
       17. The method of claim 15, wherein said step of receiving an incoming signal comprises the step of receiving a CDMA encoded signal in the frequency range of 1931.25 MHz-1988.75 MHz, said step of synthesizing a first mixing tone comprises synthesizing a signal in the frequency range of 1722.0 MHz-1779.5 MHz, said step of synthesizing a second mixing tone comprises the step of synthesizing a signal at the frequency of 206.8 MHz, and said step of generating comprises the step of generating a signal at 9.8304 MHz from an existing signal at 1.2288 MHz. 
     
     
       18. The method of claim 16, wherein said step of receiving an incoming signal comprises the step of receiving a an AMPS-encoded signal within the frequency range of 869 MHz to 894 MHz, said step of synthesizing a first mixing tone comprises synthesizing a signal within the frequency range of 952 MHz to 977 MHz, said step of synthesizing a second mixing tone comprises the step of synthesizing a signal with a frequency of 85.58 MHz, and said step of generating comprises the step of generating a signal at 9.8 MHz from an existing signal at 19.2 MHz.